How to Configure Exim on cPanel Server

cPanel uses Exim as its mail transfer agent (MTA). Proper Exim configuration is essential for reliable email delivery and preventing your server from being blacklisted.

Access Exim Configuration

WHM → Service Configuration → Exim Configuration Manager

Step 1 — Enable DKIM and SPF

WHM → Email → Enable DKIM/SPF globally:

# Via WHM command line
/usr/local/cpanel/bin/dkim_keys_install --all
/scripts/ensure_spf_records --all

Step 2 — Configure Smart Host Relay

If your server IP is blacklisted, route outbound email through a smart host:

# WHM → Exim Configuration Manager → Basic Editor
# Smart Host section:
Route all mail through a smarthost: YES
Smarthost: smtp.sendgrid.net (or your relay)
Port: 587

Step 3 — Tune Exim for Performance

# WHM → Exim Configuration Manager → Advanced Editor
# Add to main configuration section:
smtp_accept_max = 100
smtp_accept_max_per_host = 10
queue_run_max = 5
deliver_queue_load_max = 10

Step 4 — Fix Common Issues

# Check mail queue
exim -bp | head -20

# Force queue delivery
exim -qff

# Check specific message
exim -Mvh MESSAGE_ID

# Delete all frozen messages
exiqgrep -z -i | xargs exim -Mrm

Step 5 — Monitor Exim Logs

# Real-time log monitoring
tail -f /var/log/exim_mainlog

# Check for delivery failures
grep "failed" /var/log/exim_mainlog | tail -20

# Check rejected connections
grep "rejected" /var/log/exim_mainlog | tail -20

Step 6 — Configure RBL Checks

# WHM → Exim Configuration → RBLs
# Enable: zen.spamhaus.org
# Enable: bl.spamcop.net

Conclusion

Proper Exim configuration prevents blacklisting and improves delivery rates. Our team provides cPanel server management including full email configuration.